Seminar Calendar
for events the day of Thursday, September 22, 2011.

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Questions regarding events or the calendar should be directed to Tori Corkery.
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Thursday, September 22, 2011

BCDE Math/Physics Seminar
12:00 pm   in 464 Loomis Laboratory,  Thursday, September 22, 2011
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Submitted by katz.
 Charles Rezk (UIUC Math)K-theory and RealityAbstract: A "Real" space is a space equipped with an involution. Over such a space, one may define the notion of a "Real" vector bundle, which is a kind of common generalization of the notions of an ordinary vector bundle with respect to either real or complex numbers. I will discuss the resulting "Real" K-theory groups, and their relationship to Clifford modules.

Group Theory Seminar
1:00 pm   in Altgeld Hall 347,  Thursday, September 22, 2011
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Submitted by kapovich.
 Piotr Przytycki (UIUC Math)Graph manifolds with boundary are virtually specialAbstract: This is joint work with Daniel T. Wise. Let M be a graph manifold. We prove that fundamental groups of embedded incompressible surfaces in M are separable in $\pi_1(M)$, and that the double cosets of crossing surfaces are also separable. We deduce that if there is a "sufficient" collection of embedded surfaces in M, then $\pi_1(M)$ is virtually the fundamental group of a "special" CAT(0) cube complex. That is a complex that admits a local isometry into the Salvetti complex of a right-angled Artin group. We provide a sufficient collection for graph manifolds with boundary thus proving that their fundamental groups are virtually special, in particular linear.

Number Theory
1:00 pm   in 241 Altgeld Hall,  Thursday, September 22, 2011
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Submitted by berndt.
 Youness Lamzouri (UIUC)Lower bounds on odd order character sumsAbstract: In 1932, Paley established lower bounds on quadratic characters sums which are best possible, in view of conditional upper bounds of Montgomery and Vaughan. In this talk, I will show how to obtain lower bounds on odd order character sums which are best possible, unconditionally. Previously, such bounds were only known under the assumption of the Generalized Riemann Hypothesis. This is a joint work with Leo Goldmakher.